1. Technical Field
The disclosed embodiments generally relate to stereoscopic projection systems and, more specifically, relate to stereoscopic projection systems that output polarization encoded left and right eye images.
2. Background
Stereoscopic projection dates back to the early 20th century and was first seen in cinemas during the 1950s. These systems were film based and were limited mechanically to modest ˜24 Hz frame rate. As such, it was not possible to use temporal methods of providing flicker-free sequential left and right eye images for stereoscopy. Spatially multiplexed image display systems were therefore implemented. Some comprised separate projectors while others employed a single projector with each frame comprising spatially separate left and right eye images. Complex frame dividing optics was used in this latter case to successfully superimpose the images on the screen. Many systems were developed and several commercially successful, as discussed by L. Lipton in Foundations of the Stereoscopic Cinema, Van Nostrand-Reinhold, Appendix 7, p. 260, 1982, which is hereby incorporated by reference. Unfortunately the quality of the stereoscopic experience was insufficient to draw customers leading to a reversal to 2D cinema in the latter half of the century.
Stereoscopic projection has recently been revitalized with high quality advanced digital equipment encompassing capture, distribution and display. To date the most successful projection system has been developed and installed by RealD. Based on Texas instruments Digital Light Processing (DLP) technology, systems provide time sequential left and right eye images at flicker free rates. Incorporating a polarization switch in the projection path provides sequential left and right eye images for viewing through passive polarizing eyewear. While the system based on DLP technology may provide good quality stereoscopic imagery, alternative projection platforms, such as those based on liquid crystal (LC) modulation, can also be considered. Desirable features of an LC projector-based platform are potentially providing improved resolution, motion rendition, and optical polarization efficiencies. Presently, a single LC projector does not however provide time-sequential images with sufficient frame rate to allow temporal left eye/right eye polarization modulation.